This story is part of Planet Money's series on money in politics. This post was originally published on March 30. It was updated on April 6.

Most of the nitty-gritty action in Congress happens in committees.

Not surprisingly, campaign contributions flow to members of the committees that big donors are really interested in — like, say, the ways and means committee, which oversees the tax code.

This makes a huge difference to lawmakers, who need a steady stream of donations to fund their re-election campaigns.

Both parties rank each committee for its fundraising potential. There are lists of the A, B, and C committees, and fundraising targets for the members. Those lists aren't public. Many lawmakers say these lists exist, but no one would give one to us.

The analysis found that Ways and Means is the most valuable committee for fundraising. Lawmakers on the Ways and Means committee raise an extra $250,000 a year compared to the average Congressman.

The judiciary committee was the worst. Congressmen on that committee raised $182,000 less than the average Congressman.

Here's a list of the bottom three and top three committees:

One thing this graph doesn't show: The value of being a chairman.

Being a committee chairman carries huge power in Congress. Not surprisingly, it also leads to a huge fundraising boost. But the lawmakers who land these spots are expected to raise lots of money, and turn it over to the party, which spreads it around to other members.

"Where much is given, much is required," says Rep. Jeff Flake. "You're given dues, assessments, and if you're a senior member on committees that lend themselves to fundraising, and you're either a ranking member or a chairman, then you're expected to raise a lot of money. When you come up every two years to either retain your position or move to another committee, those things are certainly taken into account"

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Transcript

STEVE INSKEEP, HOST:

Santorum and those conservative activists have been discussing another candidate in the race. They want Newt Gingrich to drop out and back Santorum. That doesn't seem to be getting much traction with the Gingrich camp. One Gingrich adviser told The New York Times that Santorum's effort is, quote, "a joke." The former House speaker has repeatedly pledged to stay in the race until the Republican Convention.

In any case, surveys have suggested that if Gingrich did drop out, many of his supporters would turn to Romney, not Santorum.

Now, it costs a lot of money to win an election. In the House of Representatives, for example, it can cost anywhere between one million and $2 million to win a competitive seat, which means most lawmakers and candidates try to raise thousands of dollars every single day. One thing that makes it easier to raise money is being on the right committee.

Alex Blumberg from our Planet Money team joined NPR's Andrea Seabrook to investigate.

ANDREA SEABROOK, BYLINE: It's an open secret in Congress: If you're on the right committee, well-financed lobbies want to give you money.

ALEX BLUMBERG, BYLINE: Here is Arizona Republican Jeff Flake.

REPRESENTATIVE JEFF FLAKE: The difference between the fundraising potential when you're sitting on the Ways and Means Committee, or sitting on the Science Committee, there's a difference. There's a big difference.

BLUMBERG: The Ways and Means Committee covers the U.S. tax code - who gets tax breaks, who pays more. Every corporation in America concerned about the tax rate - which is a lot of corporations - is suddenly concerned with your candidacy when you're on Ways and Means. Science Committee can't compete with that.

SEABROOK: Now, the leaders of both parties rank each committee for its fundraising potential. There are lists of the A, B and C committees, with fundraising targets for each type. Many lawmakers confirm these lists exist, but no one would give one to us.

BLUMBERG: So we found someone who could help us build our own list.

LEE DRUTMAN: What I was trying to figure out is: Can you statistically analyze the value of these different committee seats?

BLUMBERG: Meet Lee Drutman, a PhD and senior fellow at the Sunlight Foundation, a non-partisan group that researches money in politics. We asked Drutman to crunch fundraising data going back to the early '90s. And what his results showed it's true: Ways and Means is the best committee. Members on that committee bring in an estimated $260,000 more than the average congressman.

SEABROOK: Other winning committees: Financial Services, which deals with banks, insurance companies and Wall Street. It clocks in at $182,000 more per member - Energy and Commerce, which covers the oil and natural gas industry, $142,000 over the average.

BLUMBERG: And the worst committees: It's true Government Reform is bad, as are Education and Natural Resources. They all hurt your fundraising. But the very bottom spot belongs to the Judiciary Committee, which covers the federal courts and sentencing law. Members of Judiciary bring in a whopping $182,000 less in donations than the typical member. Here's Lee Drutman.

DRUTMAN: These are fundraising dogs because you don't have jurisdiction over issues that a lot of companies with a lot of money care about. So, if you're on the Education Committee, sure, education is an important issue, but there aren't a ton of companies with a lot of money who care that much about education one way or another.

BLUMBERG: And then there's leadership. According to Drutman, having a leadership position on a committee - any committee - will often bump up your fundraising by hundreds of thousands of dollars.

SEABROOK: And if you become chairman or ranking member of a powerhouse committee, an A committee, you bring in even more. Democrat Barney Frank became a leader on the Financial Services Committee in 2003. His fundraising shot up.

REPRESENTATIVE BARNEY FRANK: People would come to see me, and pay for the privilege of doing that.

SEABROOK: But there's on catch to getting on a good committee or taking a leadership spot.

FLAKE: Where much is given, much is required.

BLUMBERG: Jeff Flake, the Republican from Arizona, says once you get on a good committee or become a chairman, your party's leadership expects you to raise even more money, and then turn it over to them. Leadership then spreads that money around to other members in tight races who don't have such an easy time of fundraising for themselves.

FLAKE: You're given dues, assessments. And if you're a senior member of committees that lend themselves to fundraising and you're either a ranking member or you are the chairman, than you're expected to raise a lot of money.

SEABROOK: Or?

FLAKE: Or when you come up, you know, every two years to either retain your position or move to another committee, those things are certainly taken into account.

SEABROOK: Do they tell you this?

FLAKE: I think that's implied. I think it's pretty well-understood.

BLUMBERG: Still, most congressmen want to get on important committees, good fundraising committees - at least that's what the data seem to say. Drutman looked and which committees congressmen join and which ones they leave.

SEABROOK: The less-lucrative committees, lawmakers don't stay on very long, like Small Business.

BLUMBERG: Important to the economy, not much fundraising potential.

DRUTMAN: Small Business is not a committee that people like to stay on. Only 18 incumbents actually switched onto that committee, and 100 of them left. So what that tells me is that if you get on the Small Business Committee, you're probably a freshman or somebody who doesn't have much influence, and you want to get off that committee as soon as possible.

SEABROOK: On the other end of the spectrum, there's Ways and Means. No surprise: 53 members transferred to that powerful committee. But in the nearly 20 years he's studied, Drutman only found four instances of members leaving it.

BLUMBERG: In other words, once you're on a fundraising giant like Ways and Means, pretty much the only way you leave is if you're voted out of office or you die. I'm Alex Blumberg.

SEABROOK: And I'm Andrea Seabrook, NPR News.

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